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## Using Unequal Tolerance Zones with Profile Feature Control Frame Dimensions

The Unequal Tolerance Zone symbol () enables you to have a profile dimension with unequal tolerance zones. PC-DMIS supports the Unequal Tolerance Zone as specified in the ASME Y14.5-2009 standard.

Requirements

- You must use a Feature Control Frame (FCF) Profile dimension (legacy dimensions do not support this).

- From the Profile dimension's XactMeasure GD&T dialog box (Insert | Dimension | <dimension>), on the Feature Control Frame tab, from the GD&T Standard list, you must select ASME Y14.5:

While unequal tolerance zones for profile are supported in the ISO 1101-2012 standard, PC-DMIS has not implemented support for this yet. So, if you choose ISO 1101 from the GD&T Standard list, PC-DMIS hides the ability to select this symbol.

Using the Unequal Tolerance Zone

If you meet the above requirements, the FCF editor in the XactMeasure GD&T dialog box has a <UZ> (unequal tolerance zone) field when you start creating a FCF Profile dimension:

Feature Control Frame Editor for a Line Profile Dimension

From the <UZ> field, you can select the Unequal Tolerance Zone symbol (). This enables the <UTol> (unequal tolerance) field where you can type the tolerance value.

Type the plus tolerance value into <UTol>. This value is always positive and must be between 0 and the total tolerance value. The minus tolerance is not visible, but it is calculated behind the scenes by subtracting the plus tolerance from the total tolerance.

For example, suppose you have a total tolerance of 0.3 and an unequal tolerance (plus tolerance) of 0.1, like this:

PC-DMIS takes the total tolerance of 0.3 and subtracts the plus tolerance of 0.1, leaving you with a minus tolerance of 0.2, as shown here:

Without the Unequal Tolerance Zone

If you don't use the unequal tolerance zone for your profile dimension, the total tolerance zone is split evenly between the plus and minus tolerances. So, if you use the above example of 0.3, you end up with a plus and minus tolerance of 0.15 each.

PC-DMIS Version Compatibility

A measurement routine after version 2010 that is loaded into a version prior to version 2010 does not display the unequal tolerance zone symbol. It also does not display the field in the Edit window. However, the unequal plus and minus tolerance zones are still applied.

A measurement routine before version 2010 that is loaded into 2010 or later displays the Unequal Tolerance Zone symbol. If tolerance zones are equal, the symbol does not appear.